Welcome to the stimulating world of Economic Systems and Theories. This broad and complex field of knowledge aims to understand, analyze, and predict human behavious and interactions in the sphere of production, distribution, and consumption of goods and services.

Economic Systems, in the simplest terms, are the means by which countries and governments distribute resources and trade goods and services. They regulate factors of production like labor, capital, and resources to satisfy consumer demands. From mixed economies that embody qualities of both capitalism and socialism, to the traditional economic systems of indigenous societies, the variety and diversity of these systems is reflective of our pluralistic world.

Economic Theories, on the other hand, are intellectual frameworks we use to understand the workings of economies. They offer explanations to economic elements like market dynamics, fiscal policies, or the effects of inflation, and build models upon which predictions can be made and policies can be designed. From the classical theories ranging from Adam Smith's "invisible hand" to Marx's historical materialism, to modern theories such as Keynesian economics, economic theories are continually evolving to explain the constantly changing economic realities.

The importance of Economic Systems and Theories in societies cannot be overstated. In a world of finite resources, how we structure our economic systems deeply affects our social fabric. Consequently, our chosen economic theory can heavily influence public policy, impacting everything from healthcare and education to energy and environmental practices.

Take, for example, capitalist societies where ownership of property and wealth is largely private and market-oriented. Its roots lie in theories promoting individual liberty and 'laissez-faire' or the belief in limited government intervention. The workings of such societies are deeply influenced by these theories. On the flip side, socialism, with its keystone belief in common ownership leading to equality and justice, models its public policy on Marxist or similar theories.

By understanding the interplay between economic systems and theories, we can critically assess the strengths and weaknesses of the socio-economic structures around us, and even contemplate frameworks that promote sustainable and equitable growth.

As we progress, bear in mind the crucial role each economic system and theory plays. They are not merely academic pursuits, but tools through which we explore, appraise, and shape realities for societies at large. We’ll dive into fascinating discussions about these systems and theories, demystifying their intricacies and evolving narratives. The exploration will provide you with a clearer lens to understand not just the economic world, but its undeniable effects on social and political landscapes. Join us on this captivating voyage, deciphering capitalism, socialism, and beyond.